Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752873AbaA3LAl (ORCPT ); Thu, 30 Jan 2014 06:00:41 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:51277 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751836AbaA3LAj (ORCPT ); Thu, 30 Jan 2014 06:00:39 -0500 Message-ID: <1391079628.26079.82.camel@shinybook.infradead.org> Subject: [PATCH v2] x86, boot: Fix word-size assumptions in has_eflag () inline asm From: David Woodhouse To: Ingo Molnar Cc: hpa@zytor.com, linux-kernel@vger.kernel.org, keescook@chromium.org, tglx@linutronix.de, hpa@linux.intel.com, linux-tip-commits@vger.kernel.org Date: Thu, 30 Jan 2014 11:00:28 +0000 In-Reply-To: <20140130090902.GA2749@gmail.com> References: <1390996897.20153.123.camel@i7.infradead.org> <20140130090902.GA2749@gmail.com> Content-Type: multipart/signed; micalg="sha-1"; protocol="application/x-pkcs7-signature"; boundary="=-j6ZRD+Q35/VnctYepgBq" X-Mailer: Evolution 3.8.5 (3.8.5-2.fc19) Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-j6ZRD+Q35/VnctYepgBq Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Commit dd78b97367bd575918204cc89107c1479d3fc1a7 ("x86, boot: Move CPU flags out of cpucheck") introduced ambiguous inline asm in the has_eflag() function. In 16-bit mode want the instruction to be 'pushfl', but we just say 'pushf' and hope the compiler does what we wanted. When building with 'clang -m16', it won't, because clang doesn't use the horrid '.code16gcc' hack that even 'gcc -m16' uses internally. Say what we mean and don't make the compiler make assumptions. Signed-off-by: David Woodhouse --- Let me know if you'd rather have this as an incremental patch. I would have preferred checking for BITS_PER_LONG=3D=3D64 rather than __x86_64__ but it seems we set that to 64 even when building the 16-bit code. arch/x86/boot/cpuflags.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c index a9fcb7c..431fa5f 100644 --- a/arch/x86/boot/cpuflags.c +++ b/arch/x86/boot/cpuflags.c @@ -28,20 +28,35 @@ static int has_fpu(void) return fsw =3D=3D 0 && (fcw & 0x103f) =3D=3D 0x003f; } =20 +/* + * For building the 16-bit code we want to explicitly specify 32-bit + * push/pop operations, rather than just saying 'pushf' or 'popf' and + * letting the compiler choose. But this is also included from the + * compressed/ directory where it may be 64-bit code, and thus needs + * to be 'pushfq' or 'popfq' in that case. + */ +#ifdef __x86_64__ +#define PUSHF "pushfq" +#define POPF "popfq" +#else +#define PUSHF "pushfl" +#define POPF "popfl" +#endif + int has_eflag(unsigned long mask) { unsigned long f0, f1; =20 - asm volatile("pushf \n\t" - "pushf \n\t" + asm volatile(PUSHF " \n\t" + PUSHF " \n\t" "pop %0 \n\t" "mov %0,%1 \n\t" "xor %2,%1 \n\t" "push %1 \n\t" - "popf \n\t" - "pushf \n\t" + POPF " \n\t" + PUSHF " \n\t" "pop %1 \n\t" - "popf" + POPF : "=3D&r" (f0), "=3D&r" (f1) : "ri" (mask)); =20 --=20 1.8.5.3 --=20 dwmw2 --=-j6ZRD+Q35/VnctYepgBq Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIISxDCCBjQw ggQcoAMCAQICAR4wDQYJKoZIhvcNAQEFBQAwfTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0 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